Oxygen concentrator



FIG. 1 is a top perspective view of an oxygen concentrator of the present invention;

FIG. 2 is a top view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a first side view thereof; and,

FIG. 6 is a second side view thereof.

Any broken lines in the drawings are for illustrative purposes only and form no part of the claimed design. 

We claim the ornamental design for an oxygen concentrator, as shown and described. 